A conventional track-type vehicle, such as a tractor, is adapted for heavy duty work during various construction and earthmoving operations. Each track assembly thereof comprises a plurality of links pivotally interconnected by pin and bushing assemblies which further function as drive lugs adapted to engage the teeth of a drive sprocket. In order to alleviate stresses imposed on such assemblies, mid-pitch drive lugs have been commonly employed to engage the drive sprocket to thus relieve stresses normally imposed on the pin and bushing assemblies. Mid-pitch drive lugs of this type are disclosed in U.S. Pat. No. 3,567,294, assigned to the assignee of this application.
In addition, conventional track assemblies oftentimes employ a rail segment on each link thereof which is adapted to engage track rollers mounted on the suspension system of the vehicle. The rail segments may be either welded or releasably connected to a respective link for replacement purposes. A disclosure of the latter construction may be found in U.S. Pat. No. 3,947,074, also assigned to the assignee of this application.
A reccurring problem in the design and fabrication of track assemblies of this type is to provide a track assembly exhibiting a high degree of structural integrity and long life expectancy. In addition, such design must also facilitate servicing and repair. For example, the rail segments and/or mid-pitch drive lugs require periodic replacement or reversal. Furthermore, the rail segments and drive lugs are secured to the track assembly independently of each other whereby the complexity and required servicing time of the track assembly are increased in comparison with the track assembly embodying the invention. Also, the bolts utilized to secure the components of a conventional track assembly together normally extend upwardly through bores formed through the links thereof.